1. Sources of the PM10 aerosol in Flanders, Belgium, and re-evaluation of the contribution from wood burning Willy Maenhaut1,2, Reinhilde Vermeylen2, Magda Claeys2, Jordy Vercauteren3 and Edward Roekens3 1Dept. Analytical Chemistry, Ghent University, Belgium 2Dept. Pharmaceutical Sciences, University of Antwerp, Belgium 3Flemish Environment Agency (VMM), Antwerpen, Belgium
EAC 2016, Tours, France

2. Introduction
In we conducted a 1-year study at 7 sites in Flanders (Belgium) to assess the contribution from wood burning (WB) to the PM10 mass and the PM10 organic carbon (OC) using levoglucosan (levo) as WB tracer and conversion factors of Schmidl et al., AE [2008], see Maenhaut et al., STE [2012]
WB PM10 mass = levo * 10.7
WB PM10 OC = levo * 5.59
In similar 1-year study at 4 urban background sites in Flanders, i.e., Antwerpen, Gent, Brugge, and Oostende
same species measured as in the study, but in addition: water-soluble inorganic species and elements
to assess WB: same approach used as in the study, but in addition: positive matrix factorization (PMF), EPA PMF 5
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3. Location of the 4 sampling sites
Brussels
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4. Sampling and analyses
From 30 June 2011 to 1 July 2012 PM10 aerosol samples simultaneously taken every 4th day at 4 sites in Flanders, Belgium
on 47-mm diam. Pallflex quartz fibre filters
PM10 mass determined by weighing of the filters at 20 °C and 50% relative humidity [done by VMM]
Organic, elemental, and total carbon [OC, EC, and TC (= OC + EC)] measured with thermal-optical instrument from Sunset Lab
using NIOSH temperature protocol, transmittance (TOT)
Levoglucosan, mannosan and galactosan determined by gas chromatography / mass spectrometry (GC/MS)
8 water-soluble ions measured by ion chromatography (IC)
15 elements determined by a combination of inductively coupled plasma atomic emission spectrometry and mass spectrometry
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5. PMF: Selected base results as a function of the number of factors
10-factor base solution retained
contributions from WB to PM10 mass and OC quite robust
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6. PMF: 10-factor base solution, factor names and key species in each factor
key species are defined as those species with typically at least one third of their mass, on average, attributed to the factor
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7. EAC 2016, Tours, France

8. PMF: wood burning (WB)
The average contributions of wood smoke for the four sites were quite substantial in winter
for the PM10 mass: from 12.5 to 20%
for the PM10 OC: from 47 to 64%
Wood burning appeared to be also a notable source of As, Cd, and Pb
these three elements had similar or higher annual median percentage apportionments to WB as K+, which is typically used as an indicator element for wood smoke
for Gent and Brugge: between 10 and 20% from WB
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9. Wood burning: levo approach vs. PMF
the data derived from levoglucosan compared very well with those obtained in our previous study using the same approach
however, the PMF data are substantially larger than those derived from levoglucosan
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10. Scatter plots of PMF-derived WB PM (brown squares) and OC (red diamonds) vs. levo and regression lines, forced through the origin
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11. Conclusion
The levoglucosan conversion factors of Schmidl et al. [2008] do not seem to be applicable for WB in Flanders
the uncertainty associated with the use of the Schmidl et al. [2008] conversion factors for Flanders was estimated to be of the order of 30% in our study [Maenhaut et al., 2012]
From scatter plots of the PMF-derived wood smoke PM10 OC and PM versus levoglucosan, we arrive at conversion factors of 9.7 and 22.6, respectively
it is recommended to use these latter factors for deriving the contribution from wood smoke when making use of levoglucosan as single marker in future studies in Flanders
it is estimated that the percentage uncertainty, which is associated with these conversion factors, is smaller than 20%
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12. Further conclusions
The impact from wood burning on the PM10 mass and OC levels in Flanders is substantially larger than previously thought
The contribution of the heavy oil burning component showed a clear tendency to decrease with distance from the coast
this was likely caused by the larger impact from ship emissions at the sites closer to the coast
The non-ferrous metals factor, which was characterized by As, Cd and Pb, exhibited by far its highest level at Antwerpen
there is a major non-ferrous metals plant in Hoboken, which is located within greater Antwerpen, and this plant is still a large source of airborne As, Cd, and Pb [VMM, 2014]
Wood burning was also a notable source of As, Cd, and Pb
these three elements had similar or higher annual median percentage apportionments to wood burning as K+, which is typically used as an indicator element for wood smoke
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13. Thank you for your attention
This work was published:
Maenhaut et al., Sci. Total Environ. 562 (2016)
Thank you for your attention
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14. EAC 2016, Tours, France